1 files changed, 17 insertions, 6 deletions

diff --git a/drivers/net/can/sja1000/sja1000.c b/drivers/net/can/sja1000/sja1000.c
index 145b1a731a53..85f7cbfe8e5f 100644
--- a/drivers/net/can/sja1000/sja1000.c
+++ b/drivers/net/can/sja1000/sja1000.c
@@ -60,7 +60,6 @@
 #include <linux/skbuff.h>
 #include <linux/delay.h>
 
-#include <linux/can.h>
 #include <linux/can/dev.h>
 #include <linux/can/error.h>
 
@@ -84,6 +83,20 @@ static struct can_bittiming_const sja1000_bittiming_const = {
         .brp_inc = 1,
 };
 
+static void sja1000_write_cmdreg(struct sja1000_priv *priv, u8 val)
+{
+        unsigned long flags;
+
+        /*
+         * The command register needs some locking and time to settle
+         * the write_reg() operation - especially on SMP systems.
+         */
+        spin_lock_irqsave(&priv->cmdreg_lock, flags);
+        priv->write_reg(priv, REG_CMR, val);
+        priv->read_reg(priv, REG_SR);
+        spin_unlock_irqrestore(&priv->cmdreg_lock, flags);
+}
+
 static int sja1000_probe_chip(struct net_device *dev)
 {
         struct sja1000_priv *priv = netdev_priv(dev);
@@ -293,11 +306,9 @@ static netdev_tx_t sja1000_start_xmit(struct sk_buff *skb,
         for (i = 0; i < dlc; i++)
                 priv->write_reg(priv, dreg++, cf->data[i]);
 
-        dev->trans_start = jiffies;
-
         can_put_echo_skb(skb, dev, 0);
 
-        priv->write_reg(priv, REG_CMR, CMD_TR);
+        sja1000_write_cmdreg(priv, CMD_TR);
 
         return NETDEV_TX_OK;
 }
@@ -346,7 +357,7 @@ static void sja1000_rx(struct net_device *dev)
         cf->can_id = id;
 
         /* release receive buffer */
-        priv->write_reg(priv, REG_CMR, CMD_RRB);
+        sja1000_write_cmdreg(priv, CMD_RRB);
 
         netif_rx(skb);
 
@@ -374,7 +385,7 @@ static int sja1000_err(struct net_device *dev, uint8_t isrc, uint8_t status)
                 cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
                 stats->rx_over_errors++;
                 stats->rx_errors++;
-                priv->write_reg(priv, REG_CMR, CMD_CDO);        /* clear bit */
+                sja1000_write_cmdreg(priv, CMD_CDO);    /* clear bit */
         }
 
         if (isrc & IRQ_EI) {